Silicon photonics is the study and application of photonic systems which use silicon as an optical medium. Silicon-based optical devices exploit the benefits of silicon while also being fully compatible with electronics. Silicon photonics has emerged as a powerful platform for photonic integration as it allows optical devices to be made cheaply using standard semiconductor fabrication techniques and integrated with microelectronic chips. With advanced lithographic capability (currently at 32 nm node, with future scaling to 22, 16, and 11 nm nodes), novel sub-wavelength optical devices can be manufactured at wafer scale. High volume production at low cost is possible by leveraging on existing semiconductor foundries. Several silicon photonic chips have been commercialized. However, they are limited to rather simple functionalities such as transmitters and receivers.
Network technical requirements and operation needs continue to evolve towards a direction in which information and services can be transmitted rapidly and at low cost to anyone, anywhere, at any time. Such a ubiquitous network will enable novel practical applications in telemedicine, immersive tele-presence and tele-education, in addition to providing the public with access to high bandwidth at low cost. The existing network cannot simply scale to realize this bold vision. The gap is experienced at the end user, as there is no cost effective means of providing high bandwidth (10 Gbit/s) applications. It is now well established that transmitting information over long distances at high data rate requires the use of optical technology. To that effect novel silicon photonic integrated circuits need to be developed. These circuits need to provide a wide variety of functions including: optical switching, optical filtering, and add-drop multiplexing—all in a compact footprint.
Silicon photonic devices can be made using existing semiconductor fabrication techniques, and because silicon is already used as the substrate for most integrated circuits, it is possible to create hybrid devices in which the optical and electronic components are integrated onto a single microchip. Thus, in addition to high speed networking, integrating sensors monolithically with photonic and electronic circuitry offers unparalleled temporal response with small size, weight and low power.